//! Browser sink for `wai.haptic.signal` — reconstructs the per-channel
//! intensity/sharpness envelope in the deterministic floor and checks
//! its hash against the corpus (sample-equivalence). Playback drives the
//! Gamepad vibration actuator / Vibration API; the waveform view is the
//! always-available presentation a sink without actuators shows.

use wai::haptic::HapticSignal;
use wasm_bindgen::prelude::*;

#[wasm_bindgen]
pub struct HapticSink {
    sig: HapticSignal,
}

fn hex(b: &[u8]) -> String {
    b.iter().map(|x| format!("{x:02x}")).collect()
}

#[wasm_bindgen]
impl HapticSink {
    #[wasm_bindgen(constructor)]
    pub fn new(whap: &[u8]) -> Result<HapticSink, JsError> {
        Ok(HapticSink { sig: HapticSignal::from_bytes(whap).map_err(|e| JsError::new(&e.to_string()))? })
    }

    pub fn num_channels(&self) -> u32 {
        self.sig.contract.channels
    }
    pub fn duration(&self) -> u64 {
        self.sig.contract.duration
    }
    pub fn sample_rate(&self) -> u32 {
        self.sig.contract.sample_rate
    }
    pub fn signal_hash_hex(&self) -> String {
        hex(&self.sig.signal_hash())
    }

    /// Reconstructed channel `c`: interleaved `[intensity, sharpness]`
    /// u8 per sample — the canonical buffer, for the waveform view and
    /// to drive the actuator.
    pub fn channel(&self, c: usize) -> Box<[u8]> {
        if c >= self.sig.channels.len() {
            return Box::new([]);
        }
        self.sig.reconstruct_channel(c).into_boxed_slice()
    }
}